Leaving things like Janna and Ardent Censor completely untouched and overpowered makes for very boring gameplay. "We can't make big changes because the pros won't have time to adapt" isn't a valid excuse for leaving monstrosities like these in the game. If anything it should be a reason to make bigger changes before worlds. You would expect the best players in the world to be able to adapt to changes quickly and figure out what is best to play. The Janna changes could've easily been pushed through and she could've been hotfixed before world's even started to prevent any problems. If you wanted to you could even do the big changes you want for worlds on the patch before the worlds patch to get rid of things like Janna and Ardent and then bugfix/hotfix accordingly during the next patch to prevent any problems during worlds. I don't understand the decision to leave the meta in such a state for the biggest lol esports event of the year.
Just as an example, in game 5 of the WE vs C9 match the KogMaw had the most bronze V positioning I've ever seen, but got away with it because of Janna and Ardent. If you disabled Ardent and Janna in worlds right now I'm sure everyone would be overjoyed and actually have a good time watching the games than watching whatever joke of a meta this is. If the best players in the world can't adapt to changes quickly, then I don't know what they're doing at worlds tbh.